Surveying devices for registering topographies of an object to be surveyed, e.g. a building or terrain, for example for surveying, testing or documentation, are known e.g. as scanners or profilers. By way of example, PCT/EP2008/009010 describes an apparatus which is able to quickly and dynamically measure distances using a moving measurement beam. Applications are simple rotational scanners or profilers aligned to the perpendicular. A surveying device for three-dimensional surveying of an object in each case registers the spatial position of a surface point of the object, i.e. the 3D coordinates thereof, by virtue of emitted laser radiation being diffusely reflected by the object surface and the distance to the targeted surface point being measured on the basis of diffusely reflected laser radiation. To this end, the surveying device has a scanning unit with a laser beam source, a deflection apparatus for swiveling the laser radiation, registering means for registering the diffusely reflected laser radiation and a detector or rangefinder. This distance measurement is linked to angle or directional information of the laser emission such that the spatial position of the registered point can be determined from these items of distance and angle information and the surface of the object can be surveyed continuously. Such surface surveying devices according to the prior art allow a user to register large surfaces and objects with relatively little time outlay—depending on a desired point-to-point resolution—completely and, optionally, with additional object information, wherein target points may be recorded at a very high rate, e.g. of several hundred thousand points per second. Hence, the distances to a multiplicity of points are able to be registered within a short period of time in a manner dependent on the respective scanning angle. A 3D point cloud is generable by such a surveying of a multiplicity of points, the 3D point cloud representing the three-dimensional nature of the object surface by means of a set of points with defined point positions in a common coordinate system. The point-to-point resolution of the registered object points and the resultant point cloud is set by the speed with which the laser beam is swiveled over the surface and by the scanning rate. By way of example, the resolution is 1.0 mm on a 100 m measurement path in the case of laser scanners.
By way of example, WO 97/40342 describes a method which records a topography by surveying devices set up in a stationary manner. For these devices, a fixed setup point is selected, which serves as a basis for a scanning process effected by motors such that the recording or scanning location (as position of the scanning unit relative to the scanned object) therefore remains unchanged during the scanning. The three-dimensional spatial information of the respective surface point is derivable by way of the distance to the measured point, the angle position at the time of the measurement and the known location of the apparatus. Here, the scanner or profiler systems, in particular the rangefinders thereof, are specifically designed for the object of registering topography and scan a surface by moving the scanning unit or by changing the beam path along one axis (profiler) or two axes (scanner).
Other methods employ mobile surface surveying devices, which scan a surface to be registered by a movement of the device, or assist or complement the scanning. PCT/EP2014/059138 discloses a mobile profiler which has a scanning unit on a surveying rod (plumb rod), which is able to be carried or displaced by a user, as a carrier. The scanning unit has a laser, with the produced laser beam being rotatable about an axis such that a laser plane is spanned, the line of intersection of which with the surface to be surveyed yields the measurement profile of a multiplicity of measurement points. Furthermore, a GNSS receiver is attached to the surveying rod for the purposes of determining the position of the surveying device. Moreover, the surveying device has a camera module, which is likewise carried by the surveying rod and optionally has an inertial measurement unit (IMU). With the aid of these means, position and orientation of the surveying rod are determined and the position and orientation of e.g. the scanning unit are determined by the fixed relative position of the units in relation to one another. Hence, it is possible to generate a point cloud, which represents the surface of the object to be surveyed, by scanning with the laser beam, taking account of the relative position or movement of the surveying device or scanning unit in relation to the surface. An advantage of a mobile or portable surface surveying device is that it is easy to change the recording location and hence it is possible to survey very extended or elongate surfaces, for example. A disadvantage of the device disclosed in PCT/EP2014/059138 is that carrying such a device is cumbersome for the user and the plumb rod is unwieldy; this holds true all the more, the longer the surveying rod is. At the same time, it would be desirable for some surveying problems, e.g. the generation of 3D coordinates of a high object such as a multistory building or an object situated far above the ground, if the scanning unit were to be positionable as high as possible or far above the ground.